BU-414: How do Charger Chips Work?

Examine the difference between a charger chip and a microcontroller.

When first introduced in the 1980s, charger chips simplified the design of NiCd and MiMH chargers, as these chemistries were difficult to charge. Li-ion is simpler and most modern chips include the protection circuits that needed to safe charge Li-ion. These are current and voltage regulation, FET switches and charge status indicators. A time-tout-timer to end charge if expected symptoms are absent is added to provide extra safety. Advanced chips also feature pre-charge conditioning (boost) for inactive batteries and a sleep mode that reduces the power when the job is done. For batteries being loaded while on charge, some chips automatically restart charge when the battery voltage falls below a preset voltage threshold.

Although charger chips are easy and economical to use, they have limitations. Most offer a fixed charge algorithm that does not permit fine-tuning for specialty uses. Chips are made for a given battery and many cannot accommodate different chemistries selectable by a code or do ultra-fast charging with safeguards that include scaling the charge current according to battery condition and temperature. Temperature control is mostly through an on/off switch.

Microcontrollers offer an alternative to charger chips. Although the design cost is higher because of programming, manufacturing costs are compatible to charger chips. It should be noted that the charge chip or microcontroller form only a small part of the charger circuit; the bulk of the cost lies in the peripheral components, which include solid-state switches, displays signals and the power supply. The cost of these parts is in direct relationship to current handling.

Last updated 2015-05-04


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Comments

On February 20, 2012 at 8:31am
Asadullah wrote:

plz tell me how much resistance is required to converts volts from high voltage to low voltage.

On February 20, 2012 at 11:12am
ResistorGuru wrote:

The answer is 2GHz.

But you might want to check out this site if you want to verify the answer: http://en.wikipedia.org/wiki/Voltage_divider…

On January 28, 2014 at 8:25am
mathavan wrote:

how to create charger with help of flyback converter without current feedback

On February 6, 2014 at 4:11pm
Alexis Pomares wrote:

Very good site. Could you comment something about some charger chips references? I mean in your so good style (referring to chemistry type, including advantages, limitations, etc).

On June 4, 2014 at 6:18am
George Mountcastle wrote:

I am making a device where I am using LI-ion batteries in a 6v pack and a 12v pack.  The 6v pack consists of 2 batteries in series and 5 of these sets in parallel. The 12 volt pack is 4 batteries in series with two sets in parallel.  The battery type is a CR123.  Does anyone make a charger or do i need to make my own?\

Please verify what I have read to be correct the max V is 4.2v/cell and current to be 1 amp.

On August 17, 2014 at 4:42am
Dave wrote:

I am making a charger which can charge 3 cell of Ni-MH cell in series and single cell Li-Ion battery, the charge algorithms should be different. Could you help how to determinate the battery type?

On June 17, 2015 at 7:23pm
Jes wrote:

any chips or MCU chip you can recommend that detects the off-the-shelf rechargeable batteries, which is the right batteries for the charging job but the user accidentally forgot to replace the non-rechargeable batteries he inserted during his trip and he plug in to recharge. Never heard of a news exploding non-rechargeable battery that were recharge but I guess the worst scenario the alkaline will leak.

I mean, any info of a chip that can detect the battery isn’t rechargeable?